I had to take my wife to the ER today had 3/4 battery when we needed to go full tank of gas about 10 miles b4 we got to ER the REX kicked on but driving aggressively to get her there ASAP battery was 2.5% it was hot here in Iowa 98 F or so and no shade in parking lot, we came out about 8 hours later. We get in it to go home says 0.0% and get charge error and no REX kicking in. but as we all know 0.00% charge is the false bottom limit set by BMW TO BAD WONT GET ME THE AN EMERGENCY 5% to get to Charge-Point or let REX Kick IN

Totally surprised since last week REX kicked in and I stopped at grocery store for 15-20 minutes on REX only and started REX and went home another 30 miles.

And its a 2014 60AH with REX

Anyone else ever had that where too low for REX to start, and low voltage 12v fully charged,

Thanks in advance,

Maverick Inventor -- Who has an interest in getting our world off of Oil based fuels -- to EV Use

iainventor, I too experienced pretty much the same thing a few weeks ago. Drive train ERROR (no battery and no REX) completely dead. My REX i3 was a recently purchased used a 2014 REX that just came off of lease with just under 25k miles on it. Had to have it towed to my dealer. Fortunately mine died in my driveway at home not as dire as your situation. I'll spare you the long version of the story here. I had it towed to my BMW dealership and it was there for about 2-1/2 weeks. They consulted with BMW i3 engineers in Germany and they determined there was a weak battery pack (there are 8 battery packs that make up the i3 EV electric drive battery) but they had to first eliminate the possibility of a bad battery controller first (there is one main controller that control all of the 8 battery packs and then each battery pack then has it’s own individual controller). Dealer was told by engineers that the fix had to be done by process of elimination, first the controllers, then the suspect battery pack and at the end of the total fix they also wanted to replace the weakened 12 volt battery that’s in the car. The cars 12 volt battery’s health also plays a role and is a factor in all of this. Picked up the car last Wednesday and put about 80 miles on it. All is well so far.

iainventor, that fateful day I had just come home on REX after using up all the battery charge in the i3 just short of arriving at my home. I plugged in my 240 volt level 2 connection to the i3 and walked away. As I sometimes do I peeked at the dashboard panel to see how the charging was coming along. It only showed that the main battery had about 18 miles of charge put into it. It should have read more than that. Checked my iPhone app and it said there was a charging error and that the main battery wasn’t charging. My garage circuit breakers checked out ok. They weren’t tripped but I reset them anyway. I unplugged the charging connector from my car and plugged it in again. Red LED error light appeared around the connection door on the car. There was what sounded to me like a relay contactor dropping out somewhere down below the car at its rear. I decided to eliminate the possibility that my 240 volt connector was faulty. So I drove to 3 EV public charging stations relatively nearby my home, 2 free municipal stations, and one pay station. All three showed the same error. By the time that I got home and parked in my driveway, I was now on REX. I turned off the power to the i3 and just for grins went for a restart. No response from the i3 after pressing the power button while applying the bake. Was DOA in my driveway thank goodness. Pressed the SOS button in the ceiling of the car, the person at the other end of the phone confirmed the i3 suffered a major drivetrain failure and that arrangements would be made to have it towed to the nearest dealer about 30 miles away. BMW German engineers told the dealer to start with replacing the main controller first then the individual battery pack controllers and then on to battery pack number #1. And if that didn’t take care of it to replace battery pack number pack #1. The dealer said that BMW engineers had to eliminate the least costlier parts before they would change out the higher cost battery pack. The cost was several thousand dollars to BMW not to mention a loner car for 2-1/2 weeks and the tow.

Thanks for your details. I had to take out about 9 lead acid batteries a 240 volt 8000 watt pure sine inverter and level 2 charger, So in about 10 minutes should of had around 450-525 watt hours filled into it. *maybe less though since read somewhere that at low % SOC cv is lower compared to 4.0 v/cell when way low maybe 3.4v/cell for awhile, so maybe only 125 watt hours.

Took off the 1772 and hit the power on. And it had just enough energy that REX engaged so I put in drive while seated in it with seat belt connected every few minutes switching from drive to reverse and back and about 10 minutes later was above 6.0% got out REX shut off so I could put away all my charging stuff in other car.

Drove it to Chargepoint Level 2 charger put about 30 miles charge on it. Then I drove it towards home about 42 miles away. Since I had all the recharge stuff in my other car with son following me home if at worst point REX DIDNT START , had enough power about 12 kw hr useable in my fla battery bank, that I would just recharge along roadside. But while driving home at about 27 miles home REX kicked on as it should have. Got home hooked up Lev 2 Wall Charger filled up like it should have.

I had the same thing happen to me on my (new to me) 2014 Rex with 45,000 miles.

Went downtown, final 5 miles or so on Rex, parked in AN UNDERGROUND PARKING GARAGE WITH 6’ 6” clearance

Went and saw a show with my wife and daughter, came out, went to start the i3 and zero battery, wouldn’t start the Rex.

Tried calling BMW Roadside assistance and getting out of this garage was going to be a fiasco. Took Uber home. Came back the next day with my portable generator and an Edison plug and ran it for about an hour. Got enough charge in it to get it to start and drive home on Rex.

I’m very concerned with how this car deals with low state of charge and the default starting point for Rex. What I think happened is when I parked I likely had 3-4% and then the fans ran for a while after parked and then there was also a delta between assumed charge by the car when it was turned off and actual charge.

I’ve seen that blog post, I found that the software is on a somewhat current version by reading the profile xml file.

Personally i’m not confident running down to 6.5% and typically will start the Rex at about 15% instead.

Supposedly the car has a new 12v and the battery pack seems to maintain a pretty good charge.